Seasonal influenza is responsible for approximately 226,000 excess hospitalizations annually and, despite effective antivirals, causes significant morbidity and mortality (estimated 30,000-50,000 deaths each year in the United States alone). The influenza virus that emerged in 2009 (A/California/07/2009 H1N1) caused fewer deaths (12,000 flu-related deaths in the U.S) but in contrast to seasonal flu, nearly 90 percent of the deaths with the 2009 H1N1 occurred among people younger than 65 years of age. NIAID has established the Influenza Research Collaboration (IRC) to conduct several multi-center studies for the treatment of influenza. NHRC will perform virologic assays in support of these multi-center studies for the treatment of influenza. These assays may include; Quantitative influenza PCR, Influenza Subtyping, Quantitative influenza virus culture (TCID50), Influenza M2 sequence looking for known mutations, Influenza NA sequence looking for known mutations, HA sequence (full) sequence looking for unknown mutations, M2 sequence (full) sequence looking for unknown mutations, NA sequence (full) sequence looking for unknown mutations, NA inhibition assay, Phenotyping, and or Microneutralization assay.